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considered clinically significant alterations in a patient. Albumin (64 to 68 kDa), potassium, and calcium loss are commonly seen in humans and small animals undergoing both dialysis and hemoperfusion. 15 , 23 In humans, albumin loss is linked to the removal

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in American Journal of Veterinary Research

Derangements of sodium and water balance are commonly reported consequences of dialysis-dependent kidney failure and must be considered when performing hemodialysis treatments. Common consequences of disordered renal sodium and water homeostasis

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in American Journal of Veterinary Research

shielded from light. Six precut 10-cm lengths of a 1-inch dialysis tube with 12- to 14-kDa pores (Carolina Biological Supply Co) were placed in distilled water for 1 hour. The distal end was folded in half along the long axis and then folded over for a

Open access
in American Journal of Veterinary Research

did not develop clinical signs until 6 years of age, which implies it may take several years for a cyst to reform and result in clinical signs again. ABBREVIATION fT4d Free thyroxine determined by equilibrium dialysis T4 Thyroxine TTF-1

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in Journal of the American Veterinary Medical Association

equine study (C max 7,460 ng/mL). 2 A single-use rapid equilibrium dialysis (RED ® , ThermoFisher Scientific) system was used according to the manufacturer’s recommendations. In brief, 500 µL of the spiked samples were added to the plasma chamber and

Open access
in American Journal of Veterinary Research

Abstract

Objective—To characterize the effect of maintenance hemodialysis on plasma amino acid concentrations and to quantitate free amino acid losses into the dialysate during hemodialysis in healthy dogs.

Animals—8 healthy adult dogs.

Procedure—Five dogs received hemodialysis treatments 3 times per week for 4 weeks. Plasma amino acid concentrations were evaluated once per week for 4 weeks in each of the 5 dogs prior to hemodialysis (time 0), 90 minutes during hemodialysis, and immediately after hemodialysis (180 minutes). Total free amino acid concentrations and plasma amino acid concentrations (time 0, 90 minutes, and 180 minutes) in the dialysate were evaluated in 3 dogs that received 1 hemodialysis treatment.

Results—Significant time versus week interactions with any plasma amino acid were not detected; however, significant decreases in all plasma amino acid concentrations measured were detected at the midpoint of dialysis (46 ± 2%) and at the end of each dialysis session (38 ± 2%). Mean (± SEM) total free amino acid loss into the dialysate was 2.7 ± 0.2 g or 0.12 g/kg of body weight.

Conclusions and Clinical Relevance—Hemodialysis is associated with significant alterations in plasma amino acid concentrations and loss of free amino acids into the dialysate. Loss of amino acids into the dialysate, coupled with protein calorie malnutrition in uremic patients, may contribute to depletion of amino acid stores.(Am J Vet Res 2000;61:869–873)

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in American Journal of Veterinary Research

Objective

To determine circulating concentrations and fate of total and free thyroxine (T4) in cats with various illnesses not associated with the thyroid glands (non-thyroidal illnesses).

Design

Prospective study.

Animals

98 cats with nonthyroidal illness and 50 clinically normal cats.

Procedure

Serum total T4 concentrations were measured by radioimmunoassay, and serum free T4 concentrations were measured by direct equilibrium dialysis. Free T4 fraction was calculated from these 2 values.

Results

Serum total T4 concentrations were significantly (P < 0.001) lower in sick cats (mean ± SD, 17.18 ± 8.14 nmol/L), compared with healthy cats (mean ± SD, 26.00 ± 7.62 nmol/L). Serum total T4 concentrations were inversely correlated with mortality. Differences in serum free T4 concentrations in sick cats (mean ± SD, 27.70 ± 13.53 pmol/L), compared with healthy cats (mean ± SD, 24.79 ± 8.33 pmol/L), were not significant. A few sick cats had serum free T4 concentrations greater than the reference range. Calculated free T4 fraction was significantly (P < 0.001) greater in sick cats (mean ± SD, 0.24 ± 0.30%), compared with healthy cats (mean ± SD, 0.10 ± 0.06%).

Clinical Implications

Euthyroidism is maintained in sick cats, despite low serum total T4 concentrations. Measurement of serum total T4 concentrations is a valuable prognostic indicator. Serum free T4 concentrations should be used cautiously as a sole diagnostic criterion for confirmation of hyperthyroidism. (J Am Vet Med Assoc 1996;208:2004-2008)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To validate a novel high-sensitivity radioimmunoassay (RIA) procedure developed to accurately measure the relatively low serum total thyroxine (T4) concentrations of birds and reptiles and to establish initial reference ranges for T4 concentration in selected species of psittacine birds and snakes.

Animals—56 healthy nonmolting adult psittacine birds representing 6 species and 42 captive snakes representing 4 species.

Procedure—A solid-phase RIA designed to measure free T4 concentrations in dialysates of human serum samples was used without dialysis to evaluate total T4 concentration in treated samples obtained from birds and reptiles. Serum T4 binding components were removed to allow assay of undialyzed samples. Assay validation was assessed by determining recovery of expected amounts of T4 in treated samples that were serially diluted or to which T4 was added. Intra- and interassay coefficient of variation (CV) was determined.

Results—Mean recovery of T4 added at 4 concentrations ranged from 84.9 to 115.0% and 95.8 to 119.4% in snakes and birds, respectively. Intra- and interassay CV was 3.8 and 11.3%, respectively. Serum total T4 concentrations for 5 species of birds ranged from 2.02 to 7.68 nmol/L but ranged from 3.17 to 142 nmol/L for blue-fronted Amazon parrots; concentrations ranged from 0.21 to 6.06 nmol/L for the 4 species of snakes.

Conclusions and Clinical Relevance—This new RIA method provides a commercially available, accurate, and sensitive method for measurement of the relatively low serum T4 concentrations of birds and snakes. Initial ranges for the species evaluated were established. (Am J Vet Res 2001;62:1750–1767)

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in American Journal of Veterinary Research

Abstract

Objective—To determine the usefulness of measuring serum free thyroxine (T4) concentration as a diagnostic test for hyperthyroidism in cats, and to determine the influence of nonthyroidal disease on free T4 concentration in cats without hyperthyroidism.

Design—Prospective case series.

Animals—917 cats with untreated hyperthyroidism, 221 cats with nonthyroidal disease, and 172 clinically normal cats.

Procedure—Serum free T4, total T4, and total triiodothyronine (T3) concentrations were measured in cats with untreated hyperthyroidism and cats with nonthyroidal disease. Serum total T4 and T3 concentrations were determined by use of radioimmunoassay, and free T4 concentration was measured by use of direct equilibrium dialysis. Reference ranges for hormone concentrations were established on the basis of results from the 172 clinically normal cats.

Results—Sensitivity of serum free T4 concentration as a diagnostic test for hyperthyroidism was significantly higher than the test sensitivity of either total T4 or T3 concentration. Of the 221 cats with nonthyroidal disease, 14 had a high free T4 concentration (ie, falsepositive result). Therefore, calculated specificity of measuring serum free T4 concentration as a diagnostic test for hyperthyroidism was significantly lower than test specificity of measuring either the total T4 or T3 concentration.

Conclusions and Clinical Relevance—Results indicate that determination of free T4 concentration is useful in the diagnosis of hyperthyroidism, especially in cats in which hyperthyroidism is suspected but total T4 and T3 concentrations are within reference ranges. However, because some cats with nonthyroidal disease have high serum free T4 concentrations, hyperthyroidism should not be diagnosed solely on the finding of high free T4 concentration. (J Am Vet Med Assoc 2001;218:529–536)

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in Journal of the American Veterinary Medical Association